The circuit was designed by two monolithic integrated circuits to measure the level of audio signals whose unit of measurement is known as volume unit. Volume Unit – an entity equal to a decibel for expressing the magnitude of a complex audio; it states the level of complex, nonrecurring, and non-periodic signals such as music and speech TL072 – a low noise JFET input operational amplifier with features such as common-mode input voltage range, high slew rate, operation without latch up, compensated internal frequency, high input impedance at the JFET input stage, low noise, low total harmonic distortion, protected from output short circuit, low input bias and offset currents, wide common-mode and differential voltage ranges, and low power consumption LM3915 – a monolithic integrated circuit that detects analog voltage levels and powers ten LEDs, LCDs or vacuum fluorescent displays, supplying a logarithmic 3 dB/step analog display which can be calibrated logarithmically and is suitable for log measurements as logarithmic bar graph driver LM3916 – a monolithic integrated circuit that detects analog voltage levels and powers ten LEDs, LCDs or vacuum fluorescent displays, supplying an electronic version of the popular VU meter which can be calibrated by decibel values and used as a bar graph/LED driver chip The VU meter specifies the non-periodic, level of complex, and non-concurrent signals like speech and music. The decibel meter and the VU meter must be treated as very different devices since the decibel meter should not be used for complex waves while the VU meter should not be used for steady-state waves. The ratio of voltage or power pertains to the unit known as decibel. The volume units are used to calibrate a volume indicator since the volume unit is a measure of a complex audio waveform. A value of -20 to +3 dB is the typical scale of a volume unit. Both IC LM3915 and LM3916 have a change of the display from a bar graph to a moving dot display by...
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